Here in Alicante, there is a large populace of Algerians(you can get a direct Ferry from Algiers
to Alicante once a week & it's busy). We don't have small boats arriving like Kent, tho further south in Costa de Sol it might be different. Most ex-pats i've met have intergrated very well & speak surprising good Spanish(i'm getting there). Glaziers view is from the 60's & 70's when criminals fled the UK to hold up in Spain, Ronnie Biggs, Buster Edwards & the like.
The great thing is, you HAVE to abide by their laws, their customs(or at least not mock/destroy them), if not, kicked out, no faffing around, no appeal(in most cases). Totally unlike soft Britain.